GB815562A - Automatic antenna coupler - Google Patents

Abstract

815,562. Automatic control systems for matching networks; inductors. COLLINS RADIO CO. June 12, 1957 [Nov. 19, 1956], No. 18588/57. Classes 38 (2) and 38 (4). [Also in Group XL (c)] An aerial tuning unit comprises an impedance-matching network having input and output lines and variable coupling means. The coupling means comprises inductor 19, Fig. 2, with variable taps 32, 27. The input line 21 is supplied by tunable signal source 23 and along its length the phase and loading conditions are monitored by the discriminators 24, 30. Mismatch on the line operates servomotors 26 and/or 31 to vary the total inductance and/or that part of it which terminates the input line. When either tap 27 or tap 32 is in the position of maximum inductance the limit switches 28 or 33 are closed and actuator motor 34 is energized, whereby switches 35, 36, 37 are operated to place capacitor 20 in series with the aerial load and the capacitor is varied from maximum to minimum in the search for the matched condition. At minimum capacity the motor 34 is reversed by switches 38, 39, the capacitor is re-connected in parallel with the output circuit by switches 35, 36, 37 its value being varied from minimum to maximum capacity, thus completing the range of impedance variation available. When a new operating frequency is selected by circuit 45, the Auto Homing Marking circuit 46 in conjunction with circuits 47, 48, 49 resets the inductor taps, the capacitor and the actuator servo switches to the positions shown ready for a new monitoring and control sequence to be performed in the line and matching network. In one embodiment of the tapped inductor, the main winding 50, Fig. 4, is wound on a ferrite core between two clamping discs 59, 60. One of the variable taps comprises two fingers 53, 54 which bridge adjacent turns and are held in each position by detent mechanism 79-82. For fine adjustment between the spaced turns of winding 50 the sliders 53, 54 are connected to a trimming winding 51 mounted on the same axis as the main winding. Winding 51 is traversed by slider 52 which, at the extremities of the winding, causes limit pins 75, 76 or 75, 77 to engage and drive round the main winding sliders. The assembly on which slider 52 is mounted is driven by motor 87 through gearing 86. A similar mechanism is mounted on the other side of winding 50 to provide a second tap. In another embodiment the winding comprises a metal ribbon 99, Fig. 5, wound in a helical groove on an insulating former 98 and on another former 97 which is conducting so that the turns wound thereon are short-circuited. Rotation of the two formers is by gearing from motor 110 which corresponds to motor 26 of Fig. 2. The other tap is effected by slider 112 mounted on the carriage 100 which rides on the helix by rollers 116. The drive is from motor 126 to splined gear wheel 120 which meshes with ring gear 113 on the carriage. Limit switches 133, 134 correspond to switches 28 and 33 of Fig. 2.